Reorganizing makefile and adding info to rootfs

Makefile

@@ -16,6 +16,8 @@ endif
 GO_BUILD:=CGO_ENABLED=$(CGO_ENABLED) $(GO) build $(GO_FLAGS) $(GO_FLAGS_EXTRA)
 
 SRCROOT=$(dir $(abspath $(firstword $(MAKEFILE_LIST))))
+# additional directories to search for rule prerequisites and targets
+VPATH=$(SRCROOT)
 
 DELTA_TARGET=out/delta.tar.gz
 
@@ -47,42 +49,47 @@ out/rootfs.vhd: out/rootfs.tar.gz bin/cmd/tar2ext4
 	gzip -f -d ./out/rootfs.tar.gz
 	bin/cmd/tar2ext4 -vhd -i ./out/rootfs.tar -o $@
 
+out/rootfs.tar.gz: out/initrd.img
+	rm -rf rootfs-conv
+	mkdir rootfs-conv
+	gunzip -c out/initrd.img | (cd rootfs-conv && cpio -imd)
+	tar -zcf $@ -C rootfs-conv .
+	rm -rf rootfs-conv
+
+out/initrd.img: $(BASE) $(DELTA_TARGET) $(SRCROOT)/hack/catcpio.sh
+	$(SRCROOT)/hack/catcpio.sh "$(BASE)" $(DELTA_TARGET) > out/initrd.img.uncompressed
+	gzip -c out/initrd.img.uncompressed > $@
+	rm out/initrd.img.uncompressed
+
+# This target includes utilities which may be useful for testing purposes.
+out/delta-dev.tar.gz: out/delta.tar.gz bin/internal/tools/snp-report
+	rm -rf rootfs-dev
+	mkdir rootfs-dev
+	tar -xzf out/delta.tar.gz -C rootfs-dev
+	cp bin/internal/tools/snp-report rootfs-dev/bin/
+	tar -zcf $@ -C rootfs-dev .
+	rm -rf rootfs-dev
+
 out/delta.tar.gz: bin/init bin/vsockexec bin/cmd/gcs bin/cmd/gcstools bin/cmd/hooks/wait-paths Makefile
 	@mkdir -p out
 	rm -rf rootfs
 	mkdir -p rootfs/bin/
+	mkdir -p rootfs/info/
 	cp bin/init rootfs/
 	cp bin/vsockexec rootfs/bin/
 	cp bin/cmd/gcs rootfs/bin/
 	cp bin/cmd/gcstools rootfs/bin/
 	cp bin/cmd/hooks/wait-paths rootfs/bin/
 	for tool in $(GCS_TOOLS); do ln -s gcstools rootfs/bin/$$tool; done
-	git -C $(SRCROOT) rev-parse HEAD > rootfs/gcs.commit && \
-	git -C $(SRCROOT) rev-parse --abbrev-ref HEAD > rootfs/gcs.branch
+	git -C $(SRCROOT) rev-parse HEAD > rootfs/info/gcs.commit && \
+	git -C $(SRCROOT) rev-parse --abbrev-ref HEAD > rootfs/info/gcs.branch && \
+	date --iso-8601=minute --utc > rootfs/info/tar.date
+	$(if $(and $(realpath $(subst .tar,.testdata.json,$(BASE))), $(shell which jq)), \
+		jq -r '.IMAGE_NAME' $(subst .tar,.testdata.json,$(BASE)) 2>/dev/null > rootfs/info/image.name && \
+		jq -r '.DATETIME' $(subst .tar,.testdata.json,$(BASE)) 2>/dev/null > rootfs/info/build.date)
 	tar -zcf $@ -C rootfs .
 	rm -rf rootfs
 
-# This target includes utilities which may be useful for testing purposes.
-out/delta-dev.tar.gz: out/delta.tar.gz bin/internal/tools/snp-report
-	rm -rf rootfs-dev
-	mkdir rootfs-dev
-	tar -xzf out/delta.tar.gz -C rootfs-dev
-	cp bin/internal/tools/snp-report rootfs-dev/bin/
-	tar -zcf $@ -C rootfs-dev .
-	rm -rf rootfs-dev
-
-out/rootfs.tar.gz: out/initrd.img
-	rm -rf rootfs-conv
-	mkdir rootfs-conv
-	gunzip -c out/initrd.img | (cd rootfs-conv && cpio -imd)
-	tar -zcf $@ -C rootfs-conv .
-	rm -rf rootfs-conv
-
-out/initrd.img: $(BASE) $(DELTA_TARGET) $(SRCROOT)/hack/catcpio.sh
-	$(SRCROOT)/hack/catcpio.sh "$(BASE)" $(DELTA_TARGET) > out/initrd.img.uncompressed
-	gzip -c out/initrd.img.uncompressed > $@
-	rm out/initrd.img.uncompressed
-
 -include deps/cmd/gcs.gomake
 -include deps/cmd/gcstools.gomake
 -include deps/cmd/hooks/wait-paths.gomake
@@ -101,8 +108,6 @@ out/initrd.img: $(BASE) $(DELTA_TARGET) $(SRCROOT)/hack/catcpio.sh
 	@/bin/echo -e '-include $(@:%.gomake=%.godeps)' >> $@.new
 	mv $@.new $@
 
-VPATH=$(SRCROOT)
-
 bin/vsockexec: vsockexec/vsockexec.o vsockexec/vsock.o
 	@mkdir -p bin
 	$(CC) $(LDFLAGS) -o $@ $^